<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>title</title>
    <script src="jquery.js"></script>
</head>
<body>
<form action="login" method="post" enctype="application/x-www-form-urlencoded">
    <input type="text" name="username" placeholder="请输入用户名"><br>
    <input type="password" name="password" placeholder="请输入密码"><br>
    <button type="submit">登录</button>
</form>
</body>
<script>
    //AJAX:Asynchronous javascript and xml
    //异步的js与xml
    //在不重载页面的条件下更新页面数据
    $('form').submit(function (ev) {
        //阻止默认事件的发生
        ev.preventDefault();
        console.log('已经阻止默认');
        //获取表单数据，自动转化成字符串序列化对
        //name=value&name=value;
        var data = $(this).serialize();

        $.post({'index.html', data, function (resData) {
                //内部参数：服务端返回的响应数据

            }
        })
    })
</script>
</html>